JPH09302061A - Biodegradable polyurethane foam and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable, flexible polyurethane foam excellent in physical properties by reacting a polyol component contg. molasses with a mixture of two specific isocyanates. SOLUTION: This polyurethane foam is obtd. by reacting a polyol component contg. molasses with a mixture of a tolylene diisocyanate-based isocyanate and a methylene diisocyanate-based isocyanate. The foam does not cause phase separation and has only one Tg; hence the reason why this foam has favorable physical properties is thought to be that the molecules of molasses are incorporated into the chains of polyurethane molecules on a molecular level. Since the tensile strength or hardness of this foam can be improved without detriment to other properties, foams suitable for aimed applications can be easily obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable polyurethane foam and a method for producing the same, more specifically, a polyurethane foam having excellent physical properties as a urethane foam, particularly a flexible urethane foam, and being biodegradable. And its manufacturing method.

[0002]

2. Description of the Related Art In recent years, attempts have been made widely to impart synthetic degradability to synthetic polymers such as plastics. Polyurethane prepared by reacting a polyol component and an isocyanate component is also biodegradable. Various attempts have been made to impart the above.

For example, Japanese Patent Publication No. 58-56605 discloses that
A hydrophilic urethane foam obtained by adding a microbial powdery organic filler to a hydrophilic urethane foam, and Japanese Patent Laid-Open No. 63-284232 discloses a vegetable fine fiber or a vegetable powder containing an ester group. There is disclosed a sheet or a molded article which is decomposed in the natural world, which is combined with a urethane resin obtained by the reaction of a polyol and an organic polyisocyanate.

In any of the above inventions, the presence of additives such as natural organic substances and vegetable fibers is essential, and it is basically not due to the decomposability of the polyurethane itself but due to the degradability of the additives.

By the way, recently, unlike the above-mentioned method, a method has been developed in which the molasses is added to the polyol component to make the polyurethane itself biodegradable (Japanese Patent Application No. 3-33402, etc.). The polyurethane obtained by this technique does not use plant fine fibers and the like, and therefore has an appearance similar to that of ordinary ones but has satisfactory biodegradability.However, since molasses is a natural product, In some cases, the polyurethane prepared by using the above cannot guarantee the required strength and elasticity, and its use may be limited depending on the intended use.

[0006]

Although it has been possible to impart substantially satisfactory biodegradability to the polyurethane itself by utilizing the above molasses, it is required to eliminate the above-mentioned problems in physical properties. SUMMARY OF THE INVENTION It is an object of the present invention to provide a biodegradable polyurethane production technique that solves this problem.

[0007]

Means for Solving the Problems In the method for producing a polyurethane using a saccharide-containing polyol, the present inventors have conducted various studies on various techniques for obtaining a polyurethane having more excellent physical properties. The inventors have found that a polyurethane having excellent physical properties can be obtained by using a combination of tolylene diisocyanate isocyanate and methylene diisocyanate isocyanate in the isocyanate component to be reacted, and completed the present invention.

That is, the present invention provides a biodegradable polyurethane foam obtained by reacting a molasses-containing polyol component with a mixture of tolylene diisocyanate isocyanate and methylene diisocyanate isocyanate, and a method for producing the same. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable polyurethane foam of the present invention uses a molasses-containing polyol component and an isocyanate component as raw material monomers for polyurethane, and further reacts with a catalyst, a foaming agent, and a foam stabilizer as appropriate. It is obtained by

A molasses-containing polyol component (hereinafter referred to as "polyol composition"), which is one of the raw materials for the biodegradable polyurethane foam of the present invention, is obtained by adding molasses to a polyol component generally used for the preparation of polyurethane. It is a thing.

Examples of the polyol component include low molecular weight polyols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, trimethylolpropane, hexanetriol, glycerin, trimethylolethane and pentaerythritol; polycaprolactone and polybasic. Polyester polyol produced from acid and hydroxyl compound; polyoxyethylene glycol, polyoxypropylene glycol, poly (oxypropylene) poly (oxyethylene)
Examples thereof include polyether polyols such as glycol, poly (oxybutylene) glycol, and poly (oxytetramethylene) glycol. Also, acrylic polyols; castor oil or tall oil derivatives can be used. This polyol component can be used in combination of several kinds, and by doing so, it is possible to change the physical properties of the polyurethane foam.

The molasses used in the polyol composition is obtained from sugar cane, sugar beet, etc.,
The molasses may be refined molasses, ice molasses, or waste molasses obtained after sugar production, but waste molasses is advantageous from the economical point of view. Further, natural molasses contains about 17 to 25% of water, but it is preferable to use the one with the water content reduced to about 3% or less.

The content of molasses in the entire polyol composition varies depending on the biodegradability required for the polyurethane foam, but is generally about 1 to 50%.

On the other hand, a mixture of tolylene diisocyanate type isocyanate and methylene diisocyanate type isocyanate (hereinafter referred to as "isocyanate composition"), which is another raw material of the biodegradable polyurethane foam of the present invention, is a tolylene diisocyanate type isocyanate ( Hereinafter, it is a mixture of "TDI isocyanate") and methylene diisocyanate-based isocyanate (hereinafter, "MDI isocyanate").

Of these, TDI isocyanates include 2,4-TDI, 2,6-TDI, and these two types of TD.
Mixtures of I, urea-modified TDI, burette-modified T
DI, carbodiimide modified TDI, etc., and as MDI isocyanate, pure MDI, crude MD
I, urea-modified MDI, burette-modified MDI, carbodiimide-modified MDI, etc. are each exemplified.

Of the isocyanate composition used in the present invention,
The ratio of TDI isocyanate to MDI isocyanate can be changed according to the physical properties required for the polyurethane foam, but in general, TDI isocyanate and MD are used.
The ratio of I isocyanate is about 95: 5 to 5:95, preferably about 80:20 to 20:80, particularly 7
It is preferably 0:30 to 50:50.

The biodegradable polyurethane foam of the present invention can be prepared according to a generally used method. That is, as a method of preparing the polyurethane chain,
Any one of the one-shot method, the prepolymer method, the quasi-prepolymer method and the like may be used, and the polyurethane foam manufacturing method may be either a slab method or a mold method.

A method for producing a biodegradable polyurethane foam by the one-shot molding method using each of the above components will be specifically described below with reference to examples.

That is, first, a polyol composition, a catalyst, a foaming agent, a foam stabilizer and a penetrant are weighed out and uniformly mixed to obtain a polyol solution. Next, the isocyanate composition is weighed out and mixed with the above polyol solution in a reaction type, and a biodegradable foam can be obtained by a contact reaction.

As the foaming agent, various ones generally used in the production of polyurethane can be used. Examples include water, organic foaming agents, and inorganic foaming agents. Examples of the organic foaming agent include nitroalkane,
Nitroureas, aldoximes, active methylene compounds, acid amides, tertiary alcohols, and oxalic acid hydrates are examples of inorganic blowing agents such as trichloromonofluoromethane, dichlorodifluoromethane, boric acid, solid carbonic acid, and hydroxylation. Aluminum etc. are mentioned. When water is used as a foaming agent, when the molasses contains water, the amount of water can be adjusted in consideration of the amount of water acting as a foaming agent.

The catalyst for controlling the reaction rate of the polyol composition and the isocyanate composition may be a catalyst commonly used in the production of polyurethane, for example,
Amines, Lewis bases of phosphines, organometallic compounds of Lewis acids (aluminum, tin) and the like can be used depending on the pot life.

In the biodegradable polyurethane foam of the present invention, the mixing ratio of the isocyanate composition is 0.5 to 2.0 times the equivalent number of all hydroxyl groups contained in the polyol composition in terms of the isocyanate equivalent number. It is about equivalent, preferably about 0.6 to 1.0 times equivalent.

As a mixing device used for stirring during reaction molding to mix and react the above-mentioned respective components into polyurethane foam, a device generally used for molding polyurethane foam, for example, a mechanical stirrer, a high-pressure stirrer, Any air mixing machine or the like can be used.

In the preparation of the biodegradable polyurethane foam of the present invention, the heat required for the reaction is given by the natural reaction heat, but depending on the reactivity of the polyol composition and the isocyanate composition used, it is 100 to 150 ° C. You may heat to about temperature.

The curing time of the obtained polyurethane foam varies depending on the kinds and ratios of the components constituting the polyol composition and the isocyanate composition, the amount of catalyst added to accelerate the reaction, and the reaction temperature. It takes 5 minutes or longer at room temperature.

The biodegradable polyurethane foam of the present invention thus obtained has a uniform cell structure and high strength as compared with the case of using TDI isocyanate or MDI isocyanate alone, as will be shown in Examples below. It may have preferable physical properties such as exhibiting rubber elasticity.

That is, in a polyurethane foam containing molasses for imparting biodegradability, when the amount of molasses in the polyol component was increased and prepared using TDI isocyanate, tensile strength, elongation at break, There is a problem that Young's modulus, 25% hardness, etc. are reduced. On the contrary, when prepared using MDI isocyanate, there were problems that phase separation occurred and the cells of the foam became rough. In contrast, TDI isocyanate and MD
When I-isocyanate is used in combination, even if a polyol component containing molasses is used, phase separation does not occur, tensile strength, 25% hardness, etc. are improved, other properties are almost unchanged, and extremely practical. Become.

[0028]

The reason why the polyurethane foam of the present invention has favorable physical properties has not been completely clarified, but molasses molecules are polyurethane molecules in molecular order in view of the fact that phase separation does not occur and Tg is 1. It is believed to be incorporated into the chain.

[0029]

EFFECTS OF THE INVENTION According to the present invention, by increasing the amount of molasses compounded, the tensile strength and hardness of polyurethane foam can be improved without changing other properties. Can be easily obtained.

[0030]

EXAMPLES The present invention will be described in more detail with reference to Examples and Test Examples, but the present invention is not limited to these Examples.

Example 1 Molasses and polyethylene glycol 200 were mixed at a ratio of 1: 2, and water was removed to 3.0% by weight with an evaporator to obtain a molasses polyol. 4.0 times the amount of polypropylene glycol based on this molasses polyol
3,000, 1.0% by weight of total weight of silicone foam stabilizer,
0.20% by weight tin catalyst, 0.25% by weight amine catalyst,
2.4% by weight of water was added as a foaming agent, and about 1,500 rp
High speed stirring was performed for 20 seconds at m.

Next, a 6: 4 isocyanate composition of tolylene diisocyanate and polymeric diphenylmethane diisocyanate was mixed in an amount of 1.02 times the equivalents of isocyanate groups to the total equivalents of hydroxyl groups, and the mixture was mixed at about 1500 rpm for 5 seconds. After stirring at high speed, the mixture was allowed to stand and foamed and cured under natural reaction heat conditions to obtain a biodegradable flexible polyurethane foam (Product 1 of the present invention).

Example 2 In the same manner as in Example 1 except that 9.0 times the amount of polypropylene glycol 3,000 was mixed with molasses polyol, biodegradable flexible polyurethane foam (product 2 of the present invention). ) Got.

Example 3 A biodegradable flexible polyurethane foam (the product 3 of the present invention) was prepared in the same manner as in Example 1 except that 2.5 times the amount of 3,000 polypropylene glycol was mixed with molasses polyol. ) Got.

Comparative Example 1 In the same manner as in Example 1 except that TDI isocyanate was used alone instead of TDI / MDI isocyanate,
A flexible polyurethane foam (Comparative Example 1) was obtained.

Comparative Example 2 A flexible polyurethane foam (Comparative Example 2) was obtained in the same manner as in Example 1 except that MDI isocyanate was used alone instead of TDI / MDI isocyanate and methylene chloride was used in combination as a blowing agent. .

Test Example 1 Physical Properties Test of Polyurethane Foam: For the polyurethane foams obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the glass transition temperature (Tg), tensile strength, elongation at break, and Young's modulus and 25% hardness were measured.
The density and the number of cells per 25 mm were also measured.
The results are shown in Tables 1 and 2.

[Tg measuring method] Using a differential scanning calorimeter, about 5 mg of a sample was packed in a sample container, which was then stored in a nitrogen stream at 1
The measurement was performed in the range of about 100 ° C. to 150 ° C. at a heating rate of 0 ° C./min. The point where the baseline change of the curve obtained by the measurement was recognized was read at the intersection point by the tangent method to determine the glass transition temperature (Tg).

[Method of Measuring Tensile Strength] Using a tensile tester, a sample cut into dumbbell type No. 1 was 300 mm / m.
The tensile strength was obtained by pulling at a test speed of in, reading the strength when the sample broke, and dividing by the cross-sectional area of the sample.

[Measurement Method of Elongation at Break] Measurement was carried out in the same manner as the method for measuring tensile strength, and elongation at break between the scores was obtained and divided by the length between the scores before the test to obtain the elongation at break.

[Young's modulus measuring method] The Young's modulus was obtained by performing the same measurement as in the tensile strength measuring method, obtaining the initial slope of the obtained strain-stress curve, and dividing it by the cross-sectional area of the sample.

[Method of measuring 25% hardness] Using a compression tester, the sample was compressed to 75% of the thickness of the sample at a test speed of 500 mm / min, and again to 25% hardness of 500 mm / m.
Compress at the test speed of in, read the strength after 20 seconds,
The 25% hardness was obtained by dividing by the area of the test piece.

Result:

[0044]

As is apparent from these results, the product of the present invention has a uniform cell structure at the macro level and a small size, and has no phase separation at the micro level and is uniform, and has high strength and excellent rubber elasticity. there were.

Test Example 2 The biodegradable polyurethane foam obtained in Example 1 was embedded in soil and its biodegradability was examined over time. As a result,
The weight loss rate after 3 weeks is 3%, and after 6 weeks and 1
The weight loss rates after 2 weeks were 7% and 35%, respectively, and the product of the present invention had sufficient natural degradability due to the addition of molasses. that's all

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Teruya Teruya, 5-1, Kyushuzaki, Gushikawa, Okinawa Prefecture Tropical Techno Center Co., Ltd. (72) Ken, Kobashigawa, 5-1, Kyusaki, Gushikawa City, Okinawa Tropic Techno Co., Ltd. In the Center (72) Inventor Yusho Tokashiki 5-1, Kyushuzaki, Gushikawa City, Okinawa Prefecture Tropical Techno Center Co., Ltd.

Claims (4)

[Claims] 1. A biodegradable polyurethane foam obtained by reacting a molasses-containing polyol component with a mixture of tolylene diisocyanate isocyanate and methylene diisocyanate isocyanate. 2. The biodegradable polyurethane foam according to claim 1, wherein the mixture of tolylene diisocyanate isocyanate and methylene diisocyanate isocyanate is a mixture of these in a ratio of 95: 5 to 5:95. 3. The biodegradable polyurethane foam according to claim 1 or 2, which is a flexible foam. 4. A method for producing a polyurethane foam by reacting a polyol component and an isocyanate component, wherein the polyol component contains molasses and the isocyanate component is a mixture of tolylene diisocyanate isocyanate and methylene diisocyanate isocyanate. A method for producing a biodegradable polyurethane foam, which is characterized in that